Resistor structure



March 27, 1962 R. E. DU BOIS 3,027,532

REsIsToR STRUCTURE Filed May 31, 1960 s sheets-sheet 1 ATTORNEY March 27, 1962 R. E. DU Bols RESISTOR STRUCTURE Filed May 31, 1960 5 Sheets-Sheet 2 Il l A rllu l Jill; YIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIA .vlllllllllm \\g :56 INVENTOR ROBERT E. DUBOIS BY Mmm/Kw4 1*/497,

ATTORNEY March 27, 1962 R. E. DU BOIS 3,027,532

RESISTOR STRUCTURE Filed May 3l, 1960 3 Sheets-Sheet 5 INVENTOR ROBERT E, DU BOIS ATTORNEY United States This invention relates generally to resistor structures and more particularly to an improved supporting structure for a zig-zag type of resistor grid. This application is a continuation-in-part of my prior application Serial No. 848,976 filed October 27, 1959, now abandoned.

The primary object of this invention is to provide an improved supporting structure for a zig-zag grid element.

A specific object of this invention is to provide an eicient, economical, supporting structure for zig-zag grid elements which will permit normal expansion and contraction of the grid in its supported position.

A further object of this invention is to provide an improved, economical supporting element for a zig-zag resistor grid in a resistor structure.

Another object of this invention is to provide a supporting structure for zig-zag grid elements in a resistor structure in which the supporting structure is readily adaptable to grids of different widths and lengths without requiring substanial part changes in the structure.

l A further object of this invention is to provide an economical combination of frame members for resistor structures which is readily suitable to supporting zig-zag grid elements of various widths.

y Another object of this invention, in a modified form, is to provide an improved resistor grid supporting clip for resistor structures.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims, certain embodiments and details of construction being illustrated in the accompanying drawings in which:

FIGURE 1 is a view in front elevation of the resistor structure comprising the invention;

FIGURE 2 is a sectioned view of the invention taken along the lines 2-2 of FIGURE l;

FIGURE 3 is a fragmentary, sectioned view in front elevation of the invention;

FIGURE 4 is a perspective view of the combined frame member and clip support structure for the grid of the invention;

FIGURE 5 is a sectioned view taken along the lines 5-5 of FIGURE 4;

FIGURE 6 is an angular view of a modified form of clip for the grid support member of this invention;

FIGURE 7 is a sectioned view in front elevation of a modified and preferred form of grid supporting clip, illustrating a fragmentary portion of a grid supported in standol relationship;

. FIGURE 8 is a sectioned view taken along the lines 8 8 of FIGURE 7; and

FIGURE 9 is a perspective view of the clip of FIG'- URES 7 and 8.

"Referring more particularly to the drawings the resistor structure 10 is illustrated as including frame mem-` bers 11 and 12 rigidly interconnected by two pairs of spaced bolts 13 and 14 and 15 and 16, each pair of which lies in a spaced, substantially parallel plane to the other pair. ySurrounding each bolt over its length is an insulating sleeve 17 of suitable insulating material such as mica. Telescoped over the sleeves 17 are regularly positioned tubular spacers 18, insulating washers 19 and the end openings 20 of grid supporting, tranvserse frame members 21. The frame members 21, which are clearly illustrated in FIGURES 2 and 4, preferably are formed by an aluminum extrusion and include a plurality of openings 22 between the end openings 20 for a purpose to be deatent f'f' 3,027,532 C Patented Mar. 27, 1962 scribed. Thus during assembly, depending on the overall, desired length of the structure, a plurality of spacers 18, washers 19 and frame members 21 are assembled in a similar fashion along each pair of frame bolts 13 and 14 and 15 and 16 over the sleeves 17. The projecting ends of the bolts are then capped with insulating grommets 23, retaining washers 24 and nuts 25 and 26. Obviously, upon tightening of the nuts, a rigid over-all frame structure is obtained.

Within the confines of the bolt and end frame members is mounted a zig-zag resistor grid 27 of suitable resistor material. The grid 27 as illustrated is formed from a single piece of material, and is folded into a plurality of spaced sections with open, curved junctures 28. Each end 29 of the grid 27 is secured by suitable means such as welding to a terminal strap 30 which is rigidly clamped about bolts 13 and 14 between insulating washers 19 during the assembly of the frame. In order to support and position the folded sections of grid 27, each transverse frame member 21 is provided with a grid juncture engaging clip 31 having a substantially H-shaped cross section. The preferred form of clip is cut from an aluminum extrusion and includes spaced, upwardly extending grid er1- gaging legs 32 and spaced downwardly extending legs 33 to be selectively attached to transverse members 21. Depending upon the width of the grid 27, one or more such `clips 3-1 may be utilized. As illustrated in FIGURE 2,

two such clips are provided on each member 21 in spaced relationship to support the grid 27. Once the particular Width of a resistor grid 27 to be utilized is known, the downwardly extending legs 33 are dimpled or otherwise deformed inwardly at 34, FIGURE 4, to rmly attached the clip 31 to a selected opening of the plural openings 22 of transverse frame members 21. Obviously, the clips are secured to the members 21 prior to general assembly of the resistor structure.

During assembly the grid 27 is positioned within the general confines of the frame members so that the junctures 28 of adjacent grid sections are received between and are supported by the upwardly extending spaced legs 32 of the clips 31 which are longitudinally spaced relative to the resistor frame bolts in their secured positions on the frame members 21. The length of each folded section of grid 27, relative to the space between the upper and lower clips 31, as viewed in FIGURE l, is such as to normally position the junctures 28 of adjacent grid sections about half the distance between the outer edges of clip legs 32 and the bridging section 35 of the clip 31. No fixed attachment is made between clip legs 32 and the folded grid sections which are thus supported in such a manner as to permit expansion and contraction of the grid along the length of each section under varying temperature conditions. Thus, while the grid 27 is restrained against transverse movement by the attachment to terminal straps '30, and the folded sections of the grid are restrained against longitudinal shifting by the clips 31, each individual folded section is capable of expansion and contraction without buckling or breaking.

FIGURE 6 illustrates a modified form of clip 36, having one pair of spaced legs 37 for engaging a transverse frame member 21, and two pairs of spaced, grid engaging legs 38. Clip 36 is formed from a piece of sheet metal with the legs 37 and 38 being cut and then bent in opposite directions from a bridging section 39. In securing a clip 36 to a cross member 21 the legs 37 are dimpled or deformed at 40 during assembly to engage an opening 22 in a member 21.

Referring now to the modified and preferred form of resistor clip 41 in FIGURES 7, 8 and 9, it will be noted that the upstanding legs 42 and 43 are provided with inwardly deformed portions or ridges 44 and 45. The

ridges 44 and 45 provide point contact with the grid 27 and thereby reduce the tendency of such structures to have hot spots. In other words, the stand-oit support between the grid 27 and the clip 41 due to the ridges 44 and 4S is such that cooling air can circulate between the legs 42 and 43 and the grid 27 to preclude or reduce hot spots in the resistor structure. The clip 41 is further provided with downwardly extending legs 4e and 47 which are dimpled at 4S and 49 respectively to engage in passage 50 of a transverse trame member 5l. It is obvious, therefore, that the clip 41 permits a free sliding action of grid Z7 when expansion and contraction occurs under varying temperature conditions, and also permits maximum cooling of the grid portion within the clip due to the stand-oit support provided by ridges 44 and 45.

The advantages of this resistor structure should now be readily apparent to one skilled in the art. The prime advantage is that the various parts of the frame assembly are readily adaptable to supporting grids of different widths and length. Thus by using somewhat longer or shorter frame bolts, a different length grid may be properly with no other part change requirement. Support of grids of dilerent widths than that illustrated is readily accomplished without requiring a part change. The structure is also adaptable to supporting plural grids in side-by-'side relationship by the same frame parts. Therefore, once a general range of grid widths, lengths, and folded section lengths is established, frame member parts may be dimensioned and produced as standard items to cover the grid range without the necessity of producing special frame parts at high cost for special resistor requirements.

Thus it is seen that this invention provides a resistor structure which provides a novel and useful manner of supporting a grid with attendant production economies. It is realized that the construction may be `subject to various obvious modications, and it is intended that the inventor be only limited to a liberal interpretation of the specification and the appended claims which would cover such obvious modifications.

I claim:

l. A resistor structure comprising a pair of frame members, means interconnecting said frame members and holding them in rigid spaced relationship, said interconnecting means including two pairs of spaced insulated bolts lying in planes normal to the frame members and normal to a plane taken longitudinally of the structure through the members, a plurality of transverse frame members interconnected between the spaced bolts at spaced intervals along the longitudinal dimension of the bolts, each said transverse member having a plurality of openings, grid supporting clip means secured to each of the transverse frame members in selected openings of said members, `and a zig-zag resistor grid carried by the clip means.

2. The invention according to claim 1 wherein the grid .is carried by the clip means in free sliding relationship therewith.

5. The invention according to claim 1 wherein each 'clip means is provided with a ridge to engage and support the grid in stand-off relationship.

4. A resistor structure comprising a pair of frame members, means interconnecting said frame members and holding them in rigid spaced relationship, said interconnecting means including two pairs of spaced insulated bolts lying in planes normal to the frame members and normal to a plane taken longitudinally of the structure through the members, a plurality of transverse frame members interconnected between the spaced bolts at spaced intervals along the longitudinal dimension of the bolts, each said transverse member having a plurality of openings, at least one H-shaped clip, including pairs of legs extending oppositely from a bridging section, secured to each transverse member by having one pair of clip legs deformed into rigid engagement with the ,member within the confines of one of the member openings, and a zig-zag resistor grid freely supported within the frame members by the nonconnected legs of said clips.

5. The invention according to claim 4 wherein said nonconnected legs of said clips are provided with ridges to engage and support the grid ina point contact, stand-orf relationship.

6. A resistor structure comprising a pair of frame members, means interconnecting said frame members and holding them in rigid spaced relationship, said interconnecting means including two pairs of spaced insulated bolts lying in planes normal to the frame members and normal to a plane taken longitudinally of the structure through the members, a plurality of transverse frame members, each said transverse member having a plurality of openings therethrough, said bolts being interconnected with said transverse members by extending through spaced openings in said members, at least one H-shaped clip, including pairs of legs extending koppositely from a` bridging section, secured to each transverse member by having one pair of clip legs deformed into rigid engagement with the member within the confines of one of the member openings, and a zig-zag resistor grid freely Supported within the frame members by the nonconnected legs of said clips.

7. A resistor structure comprising a pair of frame'` members, means interconnecting said frame members and holding them in rigid spaced relationship, said interconnecting means including two pairs of spaced insulated bolts lying in planes normal to the frame members andk normal to a plane taken longitudinally of the structure through the members, a plurality of transverse frame members, each said transverse member having ay plurality of openings therethrough, said bolts being interconnected with said transverse members by extending through spaced openings in said members, at least one clip having a grid engaging portion and a transverse member engaging portion with the member engaging portion being deformed into rigid engagement with the member within the contines of one of the member openings, and a zagzig resistor grid supported in a restrained, sliding relationship by the grid engaging portions of the clips within the frame members.

8. A resistor structure comprising a pair of frame members, means interconnecting said frame members and holding them in rigid spaced relationship, said interconnecting means including two pairs of spaced insulated bolts lying in planes normal to the frame members and normal to a plane taken longitudinally of the structure through the members, a plurality of transverse frame members, each said transverse member having a plurality of openings therethrough, said bolts being interconnected with said transverse members by extending through spaced openings in said members, at least one H-shaped clip, including a pair of grid engaging legs and a pair of member engaging legs, secured to each transverse member by having the member engaging legs deformed into rigid engagement with the member within the confines of one of the member openings, and a resistor grid formed of a strip of resistance material bent into a plurality of spaced folded sections, the grid engaging legs of each clip engaging and supporting the juncture of a pair of adjacent grid sections in a restrained, sliding relation-l ship. i 'f 9. A resistor structure comprising a plurality of members having openings therein and interconnected to form a rigid frame, a plurality of clips, including a pair of grid engaging legs and a pair of member engaging legs, secured to certain of said frame members by having the member engaging legs deformed into rigid engagement with the openings of the frame members, and a resistor grid supported by the grid engaging legs of the clips, and means carried by said clips to engage said resistor grid with a slidable point contact. v

l0. The invention according to claim 9" wherein said 5 last mentioned means comprising ridges formed in the grid engaging leg.

11. A resistor structure comprising a plurality of members interconnected to form a rigid frame, certain of said members being provided With a plurality of openings therethrough, a plurality of clips, each clip including a grid engaging portion and a member engaging portion and each clip being connected to va member with openings by having the member engaging legs deformed into rigid engagement with the member Within the oonines of one of the member openings, and a resistor grid having folded sections, each such section being supported in and by the grid engaging portions of a clip in a restrained, sliding relationship.

12. The invention according to claim 11 wherein each grid engaging portion of a clip is provided with a ridge to engage and support the grid in a point contact, standoit" relationship. v

13. A resistor structure comprising a plurality of members interconnectedy to form a rigid frame, certain of said members being provided with a plurality of openings therethrough, a plurality of H-shaped clips, each clip including a pair of grid engaging legs and la pair of member engaging legs and each clip being connected to a member with openings by having the member engaging legs deformed into rigid engagement with the member within the Comines of one ot' the member openings, and a resistor grid having folded sections, each such section being supported betweenthe grid engaging legs of a clip n a restrained, 'sliding relationship.

References Cited in the tile of this patent UNITED STATES PATENTS 1,005,805 Brown Oct. 17, 1911 2,277,912 Johnson et al Mar. 31, 1942 2,627,385 Tinnerman Feb. 3, 1953 2,839,648 Du Bois June 17, 1958 2,886,681 Bourns et al May 12, 1959 

